Locally, the City of Altus obtains its drinking water from the Tom Steed Reservoir where it is filtered before ready to drink. The 97th Air Mobility Wing additionally maintains its own water filtration system on base specifically designed for ground water, or rather, water not intended for consumption. Located more than 30 feet underground, these large water filters, known as bio walls, use naturally found microbes to purify manmade chemicals from the ground water at Altus Air Force Base, Okla.